Baw-induced Streaming, Faraday Waves, and atomization on a paper substrate

Area of Science:

• Acoustofluidics
• Microfluidics
• Paper-based analytical devices

Background:

• Acoustofluidics enables contactless manipulation with high versatility and biocompatibility.
• Microfluidic paper-based analytical devices (μPADs) offer multiplexing, rapid response, and portability.

Purpose of the Study:

• To combine acoustics with μPADs, creating Acoustic-μPADs (A-μPADs).
• To investigate acoustic field-driven flow in sessile drops on hydrophobic paper.
• To establish a flow regime map for A-μPAD applications.

Main Methods:

• Selected paper substrates based on Young's modulus and acoustic impedance.
• Developed a two-step fabrication process for hydrophobic paper to prevent liquid imbibition.
• Investigated acoustic effects on sessile drops using Micro-Particle Image Velocimetry (μPIV) and high-speed imaging.

Main Results:

• Observed and recorded acoustic streaming, Faraday waves, and atomization within a single device.
• Characterized the influence of excitation frequency and amplitude on drop behavior.
• Generated a flow regime map based on dimensionless frequency and amplitude.

Conclusions:

• Acoustic-μPADs demonstrate the capability to exhibit internal streaming, Faraday waves, and atomization.
• The developed flow regime map serves as a guide for diverse applications.
• This work lays the foundation for advanced acoustic manipulation on paper-based platforms.